在此代码中锁定的位置和内容

Question

我有一个类,其中有两个方法,一个调用一个创建并执行多个线程的类,另一个是一个事件处理程序,它处理在这些线程完成时引发的事件(然后再次调用第一个方法).

我知道处理事件的方法在引发事件的线程中运行.因此,我SyncLock一个成员变量,说明正在运行多少个线程并从中减去一个:

SyncLock Me ' GetType(me)
    _availableThreads -= 1
End SyncLock

所以我有几个问题:

主要问题:我是否应该在类中的任何地方使用SyncLock'ing _availableThreads - 即在创建线程的方法中(在创建线程时添加1)

与此问题相关的附带问题:

1. 我通常会同步SyncLock当前的实例,但我已经看到了SyncLocks类型的代码,那么同步锁定SyncLock(Current Instance)和_availableThreads？之间的区别是什么？

2. 这两者之间会有性能差异吗？并且有什么小的我可以锁定以上不影响其他任何东西 - 可能是一个单独的'挂锁'对象创建的唯一目的是锁定类中的东西？

注意:_available线程的唯一目的是控制在任何给定时间可以运行的线程数,并且线程处理可能需要数小时才能运行的作业.

码:

Public Class QManager
    Private _maxThreadCount, _availableThreads As Integer

    Public Sub New(ByVal maxThreadCount As Integer)
        Me.MaximumThreadCount = maxThreadCount
    End Sub

    Public Sub WorkThroughQueue()

        //get jobs from queue (priorities change, so call this every time)
        Dim jobQ As Queue(Of QdJobInfo) = QueueDAO.GetJobList


        //loop job queue while there are jobs and we have threads available
        While jobQ.Count > 0 And _availableThreads <= _maxThreadCount

            //create threads for each queued job
            Dim queuedJob As New QdJob(jobQ.Dequeue)
            AddHandler queuedJob.ThreadComplete, AddressOf QueuedJob_ThreadCompleted

            _availableThreads += 1 //use a thread up (do we need a sync lock here?)***************************
            queuedJob.Process() //go process the job

        End While

        //when we get here, don't do anything else - when a job completes it will call this method again
    End Sub

    Private Sub QueuedJob_ThreadCompleted(ByVal sender As QdJobInfo, ByVal args As EventArgs)

        SyncLock Me //GetType(me)
            _availableThreads -= 1
        End SyncLock

        //regardless of how the job ended, we want to carry on going through the rest of the jobs
        WorkThroughQueue()

    End Sub



#Region "Properties"


    Public Property MaximumThreadCount() As Integer
        Get
            Return _maxThreadCount
        End Get
        Set(ByVal value As Integer)
            If value > Environment.ProcessorCount * 2 Then
                _maxThreadCount = value
            Else
                value = Environment.ProcessorCount
            End If
            LogFacade.LogInfo(_logger, "Maximum Thread Count set to " & _maxThreadCount)

        End Set
    End Property

#End Region

End Class

Answer 1

你不应该SyncLock是实例或类型.你总是想要SyncLock一个完全在类控制范围内的变量,而这些变量都不是.你应该声明一个私人New Object并使用它为你的SyncLock.

Private lockObject as New Object()

...

SyncLock lockObject
   ...
End SyncLock